This invention relates to an electronic pressure responsive switch that can find particular application as a measuring member for sensing pressure fluctuations in textile machines. The pressure responsive switch is provided with a sensor component such as a proximity sensor (proximity switch member), an elastic diaphragm and an activating element adapted to move into the effective range of the sensor component.
U.S. Pat. No. 4,211,935 issued July 8th, 1980 discloses an electronic pressure responsive switch that comprises an axially displaceable electronic proximity sensor (proximity switch member), a metal plate-equipped diaphragm oriented perpendicularly to the axis of and arranged spaced from, the proximity sensor. The pressure responsive switch according to the patent further has a compression spring which is arranged coaxially about the proximity sensor and has an end which engages the metal plate. In a pressure responsive switch of this type, with increasing outer pressure applied against the metal plate-equipped diaphragm the compression spring yields so that upon reaching a predetermined setting pressure the metal plate enters into the operational (switching) zone of the electronic proximity sensor. Upon this occurrence, the thyristor forming part of the proximity sensor fires and applies a voltage to the output of the switch. As the pressure drops below a predetermined switch-on pressure, the thyristor opens, and as a result, the voltage at the switch output disappears. The electronic pressure responsive switch is a component of a regulating system in which the diaphragm forms the measuring member and the electronic proximity sensor forms the regulator of the system. It is a drawback of the above-outlined electronic pressure responsive switch that solely a two-point regulation may be effected therewith, that is, for example, in case of exceeding or dropping below a certain predetermined pressure, on-switching or off-switching takes place.